PL/SQL syntax to MySQL syntax - mysql

Question

I am trying to convert the following trigger from PL/SQL to MySQL
Especially i wanna know how to do this:
1. FOR quantity in 1..:new.product_quantity
2. FOR row IN ()
.
create or replace trigger "TRG_INSERT_BILL_PRODUCTS"
after insert on Bill_Products
for each row
begin
FOR quantity in 1..:new.product_quantity
LOOP
FOR row IN (
SELECT pa.article_id,pa.consist_quantity
FROM product_articles pa
WHERE pa.product_id=:new.product_id)
LOOP
update store
set store_quantity=store_quantity-row.consist_quantity
where article_id=row.article_id;
END LOOP;
END LOOP;
END;
Explanation of the trigger:
Store table has store.article_id and store.store_quantity for that article
Product_articles table has pa.product_id, pa.article_id (article that is consistent in the product), pa.consist_quantity (of the article)
So after inserting an product in bill, i want to find all his consisting articles and lower the store.store_quantity for that store.article_id, that would be product_quantity (how many products of that were added in the bill) * consist_quantity (of that article in the product)

Answer 1

FOR quantity in 1..:new.product_quantity
MySql hasn't FOR loop.
You can emulate it using WHILE loop:
Set quantity = 1
WHILE quantity <= :new.product_quantity DO
.....
statement_list
.....
Set quantity = quantity + 1
END WHILE
FOR row IN ( query ) LOOP ...
MySql doesn't support this kind of a loop, you must declare a cursor and process it:
DECLARE cursor_name CURSOR FOR
SELECT pa.article_id,pa.consist_quantity
FROM product_articles pa
WHERE pa.product_id=:new.product_id;
also declare a continue handler for this cursor, then explicitely open the cursor, fetch rows from it in a loop and close it.
Please refer to documentation: http://dev.mysql.com/doc/refman/5.6/en/cursors.html
to find how to use MySql cursors with examples.